System and method for accurately blending fluids

ABSTRACT

A fluid delivery system includes one or more measure modules for measuring and delivering predetermined volumes of one or more different fluids. Each measure module includes a fluid inlet port, a retention vessel, an overflow aperture to allow fluid in excess of the desired volume to flow out of the vessel, and an outlet port for dispensing the retained fluid. A calibrating rod adjustably occupies a portion of the volume of the vessel to facilitate precise adjustment of the volume of fluid dispensed by the measure module. In one particular embodiment, a blender includes a plurality of measure modules whose outputs are coupled together to produce a mixture having a composition defined by the relative capacities of the vessels of the various measure modules. In another particular embodiment, one blender dilutes a chemical concentrate, and provides the diluted mixture to another blender, which further dilutes the mixture.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention:

[0002] This invention relates generally to fluid dispensing systems, andmore particularly to a system and method for dispensing a predeterminedvolume of fluid. Even more particularly, this invention relates to asystem and method for accurately blending two or more fluids.

[0003] Onsite chemical mixing and delivery is difficult in industriesrequiring precise dilution and mixing ratios. Deterred by thedifficulties involved in producing their own chemistry, such as laborexpenses and precise molarity tolerances, industries such assemi-conductor fabrication typically purchase pre-diluted and/orpre-mixed chemicals. These pre-mixed chemicals, supplied by outsidecompanies, vary slightly in price depending on concentration. The priceper barrel of a chemical concentrate is typically only slightly higherthan that of a dilution of the same chemical. Further, the freight costof delivering multiple drums of chemicals is substantial.

[0004] Some industries opt to produce their own chemistry, but at thecost of large mixing vessels that are not typically automated. Theselarge mixing vessels are useful only to entities able to afford thesystem's maintenance costs as well as supply the space needed to housesuch a system.

[0005] Notwithstanding these limitations, onsite mixing and deliverysystems provide many advantages over purchasing pre-mixed chemicals. Byutilizing a chemical delivery and mixing system, a single barrel ofconcentrate chemical produces many times its volume in diluted solution,depending on the desired concentration of the dilute. Thus, a singlebarrel of concentrate, used to produce many barrels of dilute via achemical delivery and mixing system, greatly reduces freight costsassociated with chemical delivery. In addition, onsite dilution andmixing increases the variety of chemical concentrations and mixturesthat are immediately available, without requiring a correspondingincrease in the number of chemicals that must be purchased from chemicalmanufacturers, thereby providing the logistical and administrativeadvantage of reduced inventory.

[0006] What is needed is a compact system capable of mixing, blending,and delivering precise volumes of chemicals onsite, allowing smallindustry to manufacture chemistry in desired molarities or weight ratiosat minimal cost, and in reduced batch sizes.

SUMMARY

[0007] The present invention provides an advantage over the prior art byproviding a compact fluid delivery system capable of producing large orsmall quantities of precisely mixed chemicals on demand. The embodimentsof the invention shown herein are automated, but the present inventioncan be implemented in a manual or semi-manual system while retainingmany of the advantages of the invention.

[0008] Fluid delivery systems according to the present invention includeone or more measure modules for measuring and delivering precise volumesof fluids. Each measure module includes a fluid inlet port, a vessel, anoverflow aperture, and a fluid outlet port. The vessel receives fluidvia the fluid inlet port. The overflow aperture is positioned to definea predetermined retention capacity of the vessel, allowing excess fluidto flow out of the vessel while retaining the predetermined volume inthe vessel. The measure module measures fluid by filling the vesselbeyond its retention capacity, and then allowing the excess fluid toflow out through the overflow aperture.

[0009] An optional calibrating device (e.g., calibrating rod, slugs,inflatable bladder, etc.) facilitates fine adjustment of the retentioncapacity of the vessel. Alternatively, the position of the overflowaperture is adjustable. For example, in one embodiment the aperture isdisposed atop a vertical drain tube, such that the height of the draintube defines the retention capacity of the vessel.

[0010] An optional overflow reservoir collects the excess fluid flowingout of the vessel. The overflow fluid is transferred back into thevessel at the beginning of the next fill cycle. Use of the overflowreservoir prevents waste of expensive chemicals, and reduces the costassociated with disposal of hazardous chemicals.

[0011] One particular embodiment of the invention is capable ofoperation in two modes. In the first mode, the measure module operatesas described above. In a second mode, however, the vertical drain tubefunctions as the “vessel” by measuring the amount of fluid to bedispensed. Excess fluid flowing out of the drain tube is collected bythe vessel, which functions in the second mode as the “overflowreservoir.”

[0012] Various fluid delivery systems are constructed by interconnectinga plurality of the above-described measure modules in different ways.For example, in one embodiment a plurality of chemicals are be blendedby coupling the outputs of a like plurality of measure modules. Each ofthe measure modules measures and dispenses a particular one of theconstituent chemicals of the mixture. The relative concentration of eachchemical in the mixture depends on the retention capacity of the vesselof the measure module associated with that chemical. In anotherembodiment, the output ports of two measure modules are coupled togetherto dilute a chemical concentrate with water. The diluted mixture isprovided to other measure module pairs for further dilution, such thatthe system is able to provide several different dilutions (e.g., 10:1,50:1, 100:1, etc.) of the concentrated chemical.

[0013] In the particular embodiments shown, the fluids discharged fromthe measure modules are blended in a fluid mixing line. To facilitateeven more uniform mixing, flow controllers are interposed between thefluid output ports of the measure modules and the fluid mixing line, sothat the fluids are introduced into the fluid mixing line at a rateproportional to their relative concentration in the mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 shows one particular fluid delivery system according to thepresent invention;

[0015]FIG. 1A shows a measure module of the fluid delivery system ofFIG. 1;

[0016]FIG. 1B shows an alternate measure module for use with the fluiddelivery system of FIG. 1;

[0017]FIG. 2 shows an alternate fluid delivery system according to thepresent invention;

[0018]FIG. 3 shows another alternate fluid delivery system according tothe present invention;

[0019]FIG. 4 is a flow chart summarizing one particular method fordispensing a precise volume of fluid from a measure module according tothe present invention;

[0020]FIG. 5 is a flow chart summarizing one method of performing the“Fill Measure Module” step of FIG. 4;

[0021]FIG. 6 is a flow chart summarizing one method of performing the“Dispense Precise Volume of Fluid” step of FIG. 4; and

[0022]FIG. 7 is a flow chart summarizing one particular method ofaccurately blending a plurality of fluids according to the presentinvention.

DETAILED DESCRIPTION

[0023] The present invention overcomes the problems associated with theprior art, by providing a novel system and method for measuring,blending, and delivering precise volumes of fluid. In the followingdescription, numerous specific details are set forth (e.g. particularvalve configurations, process automation, etc.) in order to provide athorough understanding of the invention. Those skilled in the art willrecognize, however, that the invention may be practiced apart from thesespecific details. In other instances, details of well-known fluid mixingpractices (e.g. volumetric calculations for particular concentrations byreactant weight ratios) have been omitted, so as not to unnecessarilyobscure the present invention.

[0024] Further, in the particular embodiments shown, the processes andcomponent functions (e.g. valve operation, adjusting flow controllers todesired flow rates, etc.) are shown representationally to be automatedusing standard electronic control procedures (e.g. computer control).Those skilled in the art will recognize, however, that such processesand component functions may be controlled manually.

[0025]FIG. 1 shows a schematic view of a fluid delivery system 100.Fluid delivery system 100 is electronically automated by control system102. Control system 102 monitors and controls system 100 by receivingsensor signals and transmitting control signals over a communicationsnetwork 103 (e.g., a field bus, a wiring harness, etc.). Theinterconnections between communications network 103 and the variousvalves and sensors of system 100 are not shown in FIG. 1, so as not tounnecessarily obscure other features of FIG. 1, but it should beunderstood that each of the valves and sensors of system 100 communicatewith control system 102 via network 103.

[0026] Fluid delivery system 100 includes a first measure module 104, asecond measure module 106, a fluid mixing line 108, a first volumestorage module 110, and a second volume storage module 112. Firstmeasure module 104 dispenses a precise volume of a first fluid (e.g. achemical concentrate), and second measure module 106 dispenses a precisevolume of a second fluid (e.g. deionized water). The first fluid ofmeasure module 104 and the second fluid of second measure module 106 areblended in fluid mixing line 108, and selectively delivered to eitherfirst volume storage module 110 or second volume storage module 112.Measure module 104, second measure module 106, volume storage module110, and second volume storage module 112 are selectively pressurized bya pressure source 114 (e.g., compressed nitrogen gas) via a pressurevalve 115.

[0027] If only repeated delivery of a predetermined quantity of a singlefluid is required, second measure module 106 can be eliminated from thesystem. In addition, those skilled in the art will recognize that volumestorage module 110 and second volume storage module 112 are optionalcomponents of system 100, and can be eliminated if storage of blendedchemistry is not required.

[0028] Measure module 104 includes a fluid inlet port 116, a vessel 118,a shut-off valve 120, an overflow aperture 122, a calibrating device126, a fill sensor 128, an overflow sensor 129, a discharge sensor 130,a drain valve 131, a fluid discharge valve 132, and a fluid outlet port134. Fluid inlet port 116 couples vessel 118 to a source (not shown) ofthe chemical concentrate. Shut-off valve 120 allows or stops fluid flowthrough inlet port 116 into vessel 118 responsive to instructions fromcontrol system 102. Aperture 122 is disposed to define a predeterminedretention capacity of vessel 118 by permitting excess fluid to flow outof vessel 118, through drain valve 131 to drain. In the particularembodiment shown, aperture 122 is embodied in the top of vertical draintube 124, and the retention capacity of vessel 118 is grossly adjustabledepending on the height of vertical drain tube 124.

[0029] Calibrating device 126 finely adjusts the predetermined retentioncapacity of vessel 118. In the embodiment shown calibrating device 126comprises a vertically disposed rod that is adjustable to occupy avariable portion of the volume of vessel 118. Alternately, calibratingdevice 126 may comprise an inflatable bladder affixed within vessel 118and below aperture 122. In another alternate embodiment, calibratingdevice 126 may also comprise slugs of varying size and having knownvolumes that would be placed within vessel 118 and below aperture 122until the desired predetermined retention capacity is obtained.

[0030] Pressure valve 115 vents vessel 188 during the filling process.Fluid inlet valve 120 allows fluid to enter vessel 118 until one or bothof sensors 128 and 129 detect the presence of fluid at their respectivepositions. Those skilled in the art will recognize that only one of fillsensor 128 and overflow sensor 129 are required to determine when vessel118 is filled beyond aperture 122, however dual sensors facilitate amore accurate determination of when the predetermined retention capacityof vessel 118 has been exceeded, and quicker shut-off of valve 120. Inthis particular embodiment, fluid level sensor 128 is a Carlo Gavazzicapacitative sensor; part number EC3025NPAPL-10M.

[0031] Once sensors 128 and 129 determine that the retention capacity ofvessel 118 has been exceeded, shut-off valve 120 is closed, and a brieftime period is allowed for the fluid level within vessel 118 to settleat the level of aperture 122. During the settling period, fluid exitingvessel 118 via aperture 122 flows through drain valve 131 and into adrain. Completion of fluid settling can be determined from the output ofone or both of sensors 128 and 129. Alternatively, a predetermined waitperiod sufficient to allow the fluid level to settle may be employed.

[0032] After the fluid level within vessel 118 has settled at thepredetermined retention capacity, measure module 104 is ready todischarge the measured fluid. In this particular embodiment, drain valve131 is closed, and pressure valve 115 couples vessel 118 with pressuresource 114, thereby pressurizing vessel 118 to accelerate the dischargeof fluid through fluid outlet port 134. Those skilled in the art willrecognize, however, that pressurizing vessel 118 is not an essentialelement of the invention, and that the invention may be practiced, forexample, by allowing vessel 118 to drain by gravity or other means.

[0033] After vessel 118 is closed, and responsive to instructions fromcontrol system 102, discharge valve 132 opens, allowing the fluid invessel 118 to be dispensed from measure module 104 via fluid outlet port134. Discharge sensor 130 generates a signal to indicate that thedispensing process is complete, when sensor 130 no longer senses thepresence of fluid.

[0034] Second measure module 106 is similar to measure module 104 inboth structure and function, except that measure module 106 typicallydelivers a second fluid that is chemically different from the fluiddelivered by measure module 104. Accordingly, the predeterminedretention capacity of second measure module 106 is selected with respectto the retention capacity of measure module 104 to yield a particularmix concentration when the fluids of the measure modules 104, 106 aremixed. In the case where the second fluid is deionized water, mixing thefluid of measure module 104 and the deionized water of second measuremodule 106 results in a precise dilution of the fluid of measure module104.

[0035] The fluids dispensed from measure module 104 and second measuremodule 106 are blended in fluid mixing line 108. To control the rate ofblending of the fluids, a flow controller 138 is interposed betweenfluid outlet port 134 and fluid mixing line 108, and a second flowcontroller 140 is interposed between a fluid outlet port 142 of secondmeasure module 106 and fluid mixing line 108. Flow controllers 138 and140 can be adjusted to deliver fluid at desired flow rates manually orby control system 102. Ideally, fluid dispensed by both measure module104 and second measure module 106 are dispensed over the same timeinterval to facilitate uniform blending of the fluids.

[0036] Volume storage module 110 and second volume storage module 112facilitate storage of batches of the blended fluid exiting fluid mixingline 108. Volume storage module 110 contains a fluid inlet port 144 forreceiving blended fluid from fluid mixing line 108, a holding chamber146 for storing blended fluid, and a fluid discharge port 148 fordischarging stored fluid. Second volume storage module 112 issubstantially similar to volume storage module 110, and includes a fluidinlet port 150, holding chamber 152, and a fluid discharge port 154. Apair of valves 155, 157 selectively pressurize or vent volume storagemodule 110 and second volume storage module 112, respectively,responsive to control signals from control system 102, in order tofacilitate the filling and dispensing of fluid from volume storagemodules 110, 112. While using two volume storage modules has theadvantage that one volume storage module can provide fluid to a systemprocess while the other volume storage module is being filled, using twovolume storage modules is not an essential element of the invention, andthe invention may be practiced with a single volume storage module ormore than two volume storage modules.

[0037] A first steerage valve 156 and a second steerage valve 158 directfluid flow into either volume storage module 110 or second volumestorage module 112, responsive to control signals from control system102. If a particular batch of fluid mixture from mixing line 108 is tobe delivered to volume storage module 110, then steerage valve 158 isplaced in the closed position and steerage valve 156 is placed in theopen position, to direct fluid from mixing line 150 through steeragevalve 156 and into volume storage module 110. On the other hand, if aparticular batch of fluid mixture from mixing line 108 is to bedelivered to second volume storage module 112, then steerage valve 158is placed in the open position and steerage valve 156 is placed in theclosed position, to direct fluid from mixing line 150 through steeragevalve 158 and into second volume storage module 112. Optionally,steerage valves 156 and 158 are embodied in a single valve thatselectively couples fluid mixing line 108 with volume storage module 110and second volume storage module 112.

[0038] Volume storage module 110 and volume storage module 112 arefitted with sensors to provide feedback to control system 102 regardingthe amount of fluid stored in volume storage modules 110 and 112. Eachvolume storage module is fitted with a fill signal sensor 160, adispense signal sensor 162, and a low fluid sensor 164.

[0039] When the fluid level in volume storage module 110 falls below thefluid level defined by the placement of fill signal sensor 160, fillsignal sensor 160 transmits a fill signal to control system 102. Uponreceipt of the fill signal, control system 102 causes measure module 104and second measure module 106 to fill to their respective predeterminedretention capacities. Fill signal sensor 160 of second volume storagemodule 112 functions similarly.

[0040] When the fluid level in volume storage module 110 falls below thefluid level defined by the placement of dispense sensor 162, dispensesignal sensor 162 transmits a dispense signal to control system 102.Upon receipt of a dispense signal from volume storage module, controlsystem 102 sets valves 156 and 158, and causes measure module 104 andsecond measure module 106 to dispense their contents into volume storagemodule 110. Dispense sensor 162 of second volume storage module 112functions similarly. In a particular embodiment the volume held involume storage module 110 and second volume storage module 112 betweenfill signal sensor 162 and dispense signal sensor 164 comprises thetotal volume of fluid dispensed by measure module 104 and second measuremodule 106.

[0041] When the fluid level in volume storage module 110 falls below thefluid level defined by the placement of low fluid sensor 164, low fluidsensor 164 transmits a low fluid signal to control system 102 toindicate a dangerously low volume of fluid in volume storage module 110.In an alternate embodiment, volume storage module 110 and second volumestorage module 112 have only a low fluid sensor instead of fill signalsensor 160 and dispense fluid sensor 162. In that embodiment, when thefluid level within volume storage module 110 reaches the level definedby the placement of low fluid sensor 164, low fluid sensor generates alow fluid signal to control system 102. Upon receipt of the low fluidsignal, control system 102 transmits signals to measure module 104 andsecond measure module 106 causing them to both fill and dispense.

[0042] A process supply valve 166 selectively couples process supplyport 168 with one of fluid discharge port 148 and fluid discharge port154 of volume storage modules 110 and 112, respectively. Volume storagemodule 110 and second volume storage module 112 dispense their storedfluids to a system process, via process supply valve 166, out through aprocess supply port 168. In a particular embodiment, volume storagemodule 110 and second volume storage module 112, operate in alternatingfashion. In particular, volume storage module 110 is vented and filledwhile second volume storage module 112 is pressurized and dispensingfluid, and vice versa.

[0043] Those skilled in the art will recognize that variations to theabove-described fluid delivery system are possible without deviatingfrom the scope of the invention. For example, an alternate embodiment ofthe present invention includes only one volume storage module 110, andfluid mixing line 108 is optional. If fluid mixing line 108 is omitted,fluid outlet port 134 and fluid outlet port 142 coupled directly to atleast one fluid inlet port 144 of volume storage module 110. In anotherparticular embodiment, fluid delivery system 100 comprises a singlemeasure module 104 and no volume storage module. This particularembodiment is useful in applications (e.g., packaging systems, bottlingsystems, etc.) where repeated dispensations of a precise volume isrequired.

[0044]FIG. 1A shows an alternate measure module 104A, which is similarto measure module 104, but is modified to conserve fluid and prevent thedischarge of hazardous chemicals into a drain. Measure module 104Aincludes an overflow reservoir 170, an overflow pressure valve 172, aninlet flow controller 174, an inlet check valve 176, and a directionalvalve 178.

[0045] Overflow reservoir 170 receives and stores excess fluid thatflows out of vessel 118 via aperture 122 during a fill cycle. Overflowpressure valve 172 selectively couples overflow reservoir 170 withpressure source 114, so that overflow reservoir 170 can be pressurizedto push any fluid stored in reservoir 170 back into vessel 118 at thebeginning of the next fill cycle. Overflow reservoir 110 thus preventsunnecessary fluid loss, which results in cost savings, particularly ifthe fluid being dispensed is relatively expensive. In addition, overflowreservoir 170 helps reduce disposal costs for chemicals which cannot bedischarged into public wastewater systems without treatment. A fillsensor 171 in overflow reservoir 170 serves as an alternate or redundantsensor to fill sensor 128, by detecting the presence of liquid inoverflow reservoir 170.

[0046] Those skilled in the art will realize, however, that overflowreservoir 110 (as well as other elements, even if not specificallymentioned) is not an essential element of the present invention. Forexample, if the excess fluid flowing out of vessel 104 were water,overflow reservoir 110 would not be needed to retain the excess fluidbecause water is both inexpensive, and environmentally safe. As shown inthe embodiment of FIG. 1, such innocuous fluids can be dischargeddirectly into a drain.

[0047] Measure module 104A also differs from measure module 104 in thatfluid flows into and out of vessel 118 via a common line 179.Directional valve 178 selectively couples common line 179 with fluidinlet port 116 and fluid outlet port 134 to fill and discharge fromvessel 118, respectively. During a fill cycle, incoming fluid flows inthrough inlet port 116, through valves 176, 174, 120, and 178, throughcommon line 179, past sensor 130, and finally into vessel 118. Inletcheck valve 176 limits fluid flow entering measure module 104A to asingle direction. Inlet flow controller 174 controls the flow rate offluid entering vessel 118 in order to reduce ebullition of the fluid asit enters vessel 118. Shut-off valve 120 starts and stops the flow ofincoming fluid. During a discharge cycle, fluid flows out of vessel 118,through common line 179, through directional valve 178, throughdischarge valve 132, and out fluid outlet port 134.

[0048] An alternate overflow aperture 122A and an alternate overflowsensor 129A are shown in dashed lines in FIG. 1A to make clear that itis not essential for overflow aperture 122 to disposed atop a verticaldrain tube. For example, aperture 122A is disposed in the wall of vessel118. Nevertheless, the position of aperture 122A will roughly define theretention capacity of vessel 118, the same as overflow aperture 122.

[0049]FIG. 1B shows another alternate measure module 104B. Measuremodule 104B is similar to measure module 104A, but is modified toinclude a vessel selection fill valve 180, an overflow selection valve182, a first vessel valve 184, a second vessel valve 186, and adischarge selection valve 188. These valves are coupled as shown in FIG.1B to facilitate the selective use of either vessel 118 or verticaldrain tube 124 as the vessel whose retention capacity determines theoutput of measure module 104B. In other words, measure module 104B canselectively deliver precise volumes of fluid corresponding to either thepredetermined retention capacity of vessel 118 or the predeterminedretention capacity of vertical drain tube 124.

[0050] In a first mode of operation, measure module 104B operatessimilar to measure modules 104 and 104A described above. During the fillprocess, vessel selection fill valve 180 and second vessel valve 186couples fluid inlet port 116 with common line 179 to allow fluid to flowinto vessel 118. Overflow selection valve 182 couples vertical draintube 124 with overflow reservoir 170 to direct the flow of excess fluidinto overflow reservoir 170. During the discharge process, second vesselvalve 186 and discharge selection valve 188 couple common line 179 withfluid outlet port 134, to allow fluid from vessel 118 to flow out offluid outlet port 134. As in previously described embodiments, fluiddischarge valve 132 selectively allows or interrupts the flow of fluidout of measure module 104B.

[0051] In a second mode of operation, vertical drain tube 124 is used tomeasure the fluid instead of vessel 118, thereby facilitating precisevolumetric metering of a small amount of fluid, and vessel 118 serves asan overflow reservoir. During a fill process in the second mode ofoperation, vessel selection fill valve 180, first vessel valve 184, andoverflow selection valve 182 couple vertical drain tube 124 with fluidinlet port 116, to allow fluid to flow into vertical drain tube 124.Shut-off valve 120 allows fluid to flow into vertical drain tube 124until fluid overflowing from vertical drain tube 124 is sensed bydischarge sensor 130.

[0052] During the discharge process, in the second mode of operation,the fluid retained in vertical drain tube 124 is discharged out ofmeasure module 104B via fluid outlet port 134. To facilitate dischargeof the fluid from vertical drain tube 124, overflow selection valve 182,first vessel valve 184 and discharge selection valve 188 couple verticaldrain tube 124 with fluid outlet port 134, via discharge valve 132.Fluid delivery continues until overflow sensor 129 senses that no fluidis flowing out of vertical drain tube 124.

[0053] Any fluid remaining in vessel 118 can be handled in a number ofways. For example, if the next fill cycle is to occur under the firstmode of operation (filling vessel 118) then the fluid can simply be leftin vessel 118. However, if the next fill cycle is to occur under thesecond mode of operation (filling drain tube 124) then the excess fluidin vessel 118 can be evacuated by coupling vessel 118 with overflowreservoir 170 (e.g., via common line 179, valve 186, valve 188, valve184 and valve 182), and pressurizing vessel 118 to force the retainedfluid into overflow reservoir 170.

[0054]FIG. 2 shows a dilution system 200 that supplies multiple dilutionratios of a concentrate fluid to one or more system processes. Dilutionsystem 200 includes a first blender (A) 202, a second blender (B) 204,and a third blender (C) 206. Each of blenders 202, 204, and 206 aresubstantially similar to fluid delivery system 100, described in FIG. 1,and may include any of alternate measure modules 104, 104A, or 104B. Thecomponents of dilution system 200 are controlled by a control system201, via a field bus system (not shown).

[0055] Each of fluid delivery systems 202, 204, and 206 includes a firstfluid inlet port 203 coupled to receive a diluting fluid (typicallydeionized water) via a fluid supply line 207. Each of fluid deliverysystems 202, 204, and 206 also includes a second fluid inlet port 205,for receiving a concentrate fluid, and a fluid outlet port 210 fordispensing a mixture of the diluting fluid and the concentrate.

[0056] Second fluid inlet port 205 of blender A 202 is coupled toreceive a concentrated fluid (e.g., sulfuric acid), via a fluid supplyline 208. Blender A 202 blends the concentrated fluid with the dilutingfluid to obtain a mixture with the desired concentration. Theconcentration of the mixture depends on the relative capacities of themeasure modules (not shown in FIG. 3) of blender 202. In this particularexample, a 10:1 mix ratio is obtained. In other words, the concentrationof diluted fluid exiting fluid outlet port 210 is exactly {fraction(1/10)} the concentration of the fluid entering fluid delivery system202 via fluid input line 208.

[0057] Blender B 204 facilitates further dilution of the diluted fluidproduced by blender A 202. Second fluid input port 210 of blender B 204is coupled to received fluid from fluid output port 210 of blender A. Inthis particular embodiment, the relative capacities of the measuremodules of blender B 204 are 5:1, such that blender B204 dilutes thefluid received via second fluid inlet port 205 with the diluting fluidreceived via first fluid inlet port 203 to obtain a mixture with ⅕ theconcentration of the incoming fluid. Therefore, the concentration ratioof the fluid produced by blender B 204 from the fluid received fromblender A 202 is {fraction (1/50)} ({fraction (1/10)}×⅕) theconcentration of the chemical concentrate supplied by supply line 208.

[0058] Blender C 206 also facilitates further dilution of the dilutedfluid produced by blender A 202 to yield a fluid having yet anotherconcentration. Second fluid input port 210 of blender C 206 is coupledto received fluid from fluid output port 210 of blender A. In thisparticular embodiment, the relative capacities of the measure modules ofblender C 204 are the same as blender A 202 (10:1), such that blender C206 dilutes the fluid received via second fluid inlet port 205 with thediluting fluid received via first fluid inlet port 203 to obtain amixture with {fraction (1/10)} the concentration of the incoming fluid.Therefore, the concentration ratio of the fluid produced by blender B204 from the fluid received from blender A 202 is {fraction (1/100)}({fraction (1/10)}×{fraction (1/10)}) the concentration of the chemicalconcentrate supplied by supply line 208.

[0059] As described above, dilution system 200 is able to simultaneouslyprovide three different dilutions (10:1, 50:1, and 100:1) of thechemical concentrate supplied via supply line 208. Those skilled in theart will recognize, however, that dilution system 200 is not limited tothe example dilution ratios shown therein, and may be adapted to providemore and/or different concentrations than those shown. In fact, it iscontemplated that the measure modules of the blenders be easilyinterchangeable, so that the blenders can be easily modified to produceany desired concentrations that are required to meet the needs of anindividual user.

[0060]FIG. 3 shows a fluid delivery system 300 for blending more thantwo different fluids, as is required in many applications. Fluiddelivery system 300 includes control system 302, a plurality of measuremodules 304(1−n), a fluid mixing line 308, a first volume storage module310, a second volume storage module 312, and a discharge selection valve314. Measure modules 304(1−n) are substantially similar to the measuremodules 104, 104A or 104B described above. However, the details of eachmeasure module 304(1−n) are omitted from FIG. 3 so as not tounnecessarily obscure the features of the present invention emphasizedtherein.

[0061] Each of measure modules 304(1−n) includes a fluid inlet port 316and a fluid outlet port 334. Each of measure modules 304(1−n) receives aparticular fluid constituent of the blended product via its respectivefluid inlet port 316(1−n). Responsive to a signal from control system302, each of measure modules 304(1−n) dispenses a predetermined volumeof its respective fluid, via its respective fluid outlet port 334(1−n),into fluid mixing line 308. The blended fluid exiting fluid mixing line308 is directed into either volume storage module 310 or second volumestorage module 312 by steering valve 320. Discharge selection valve 314selectively couples one of volume storage module 310 and second volumestorage module 312 to process supply port 368 to supply blended fluid tosystem process.

[0062] The present embodiment illustrates many advantages associatedwith the present invention. For example, many different fluids can beblended into a precise volume of a complex fluid having a knownconcentration of each of the constituent fluids. Further, having manymeasure modules operating in parallel facilitates the delivery of largerquantities of deliverable chemistry.

[0063]FIG. 4 shows a flowchart summarizing a method 400 for dispensing aprecise volume of fluid from a measure module according to the presentinvention. In a first step 402, control system 102 determines whetherthere is a fluid delivery request (e.g., a signal from one of volumestorage modules 146, 152). If in first step 402, control system 102 doesnot detect a fluid delivery request is, then control system 102 repeatsfirst step 402 until a request is detected. If, however, in first step402, control system 102 detects a fluid delivery request, then method400 proceeds to a second step 404 where control system 102 opensshut-off valve 120, allowing fluid to flow into vessel 118 until vessel118 is filled beyond its predetermined retention capacity. Then, in athird step 406, control system 102 closes shut-off valve 120, and theexcess fluid contained within vessel 118 is drained, via aperture 122,until the fluid volume within vessel 118 settles at the predeterminedretention capacity of vessel 118. Next, in a fourth step 408 controlsystem 102 opens fluid discharge valve 132 to dispensing the precisevolume of stored fluid from vessel 118 out through fluid outlet port134. Then method 400 ends.

[0064]FIG. 5 shows a flowchart summarizing a method 500 of performingstep 404 of method 400 for filling a measure module (e.g., 104, 104A, or104B) according to the present invention. In a first step 502 controlsystem 102 vents vessel 118 and pressurizes overflow reservoir 170 totransfer any excess fluid retained in overflow reservoir 170 back intovessel 118 via aperture 122. Then, in a second step 504, control systemopens shut-off valve 120 to begin filling vessel 118 via fluid inletport 116. Next, in a third step 506, control system 102 determineswhether the level of fluid in vessel 118 has exceeded the predeterminedretention capacity of vessel 118 (e.g., by sensor 129 sensing overflowfluid). Third step 506 is repeated while vessel 118 fills, until thefluid level in vessel 118 exceeds its retention capacity. Then, in afourth step 508 control system 102 closes shut-off valve 120 to haltfluid delivery to vessel 118.

[0065]FIG. 6 shows a flowchart summarizing one method 600 for dispensinga precise volume of fluid according to fourth step 408 of method 400.For the purposes of this example, volume storage module 110 is intendedto be the recipient of the dispensed fluid of measure module 104, but itshould be clear that method 600 can also be used to dispense fluid intosecond volume storage module 152, or to any other container or process.In a first step 602, control system 102 vents volume storage module 110,via valve 155, to depressurize volume storage module 110. Then, in asecond step 604, control system 102 pressurizes vessel 118, via valve115, to urge the retained fluid out of vessel 118. In a third step 606,control system 102 opens discharge valve 132 to allow the pressurizedfluid flow from vessel 118, via fluid outlet port 134, to volume storagemodule 110. In a fourth step 608, control system 102 checks to determinewhether all of the fluid has been transferred from measure module 104 tovolume storage module 110. Fourth step 608 is continued as long asdischarge sensor 130 indicates that fluid is still flowing from vessel118. When the discharge of fluid is complete, then in fifth step 610,steerage valve 156 closes to stop any fluid from entering or exiting(e.g. blended fluid or pressurized gas) volume storage module 110. Next,in a sixth step 612, volume storage module 110 is coupled, via valve155, with pressure source 114, to repressurize volume storage module110. Then method 600 ends.

[0066]FIG. 7 shows a flowchart 700 summarizing a method of accuratelyblending a plurality of fluids in accordance with the present invention.In a first step 702, control system 102 waits for a fill signal fromvolume storage module 110 or second volume storage module 112 indicatingthat a batch of the blended fluid is required. Upon receipt of a fillsignal, then in a second step 704, control system fills vessel 118 offirst measure module 104 with a first fluid, and fills vessel 141 ofsecond measure module 106 with a second fluid. In a third step 706control system 102 waits for a dispense signal from volume storagemodule 110 or second volume storage module 112.

[0067] Once a dispense signal is received (e.g., from volume storagemodule 146), then in a fourth step 708, control system 102 depressurizesvolume storage module 146. Next, in a fifth step 710, control system 102pressurizes vessel 118 of measure module 104 and vessel 141 of measuremodule 106. In a sixth step 712, the discharge valves (e.g., 132) ofeach of measure modules 104 and 106 are opened to allow the fluidscontained in the respective measure modules to flow into mixing line 108at a rate determined by flow controllers 138 and 140. Control system 102directs the flow of blended fluid from mixing line 108 into the volumestorage module 146 by opening steerage valve 156 and closing steeragevalve 158.

[0068] In a seventh step 714, control system 102 monitors the dischargesensors (e.g., sensor 130) to determine when measure modules 104 and 106have finished transferring their entire contents to volume storagemodule 146. Then, in an eighth step 716, control system 102 closessteerage valve 156, fluid discharge valve 132, and fluid discharge valve143, and in a ninth step 718, repressurizes volume storage module 160 tofacilitate delivery of fluid to a system process.

[0069] While the example method described above includes filling twomeasure modules with fluid, those skilled in the art will understandthat method 700 can be implemented with any desirable number of measuremodules, as suggested by the embodiment of FIG. 3.

[0070] The description of particular embodiments of the presentinvention is now complete. Many of the described features may besubstituted, altered or omitted without departing from the scope of theinvention. For example, alternate calibrating devices 126 (e.g. slugshaving predetermined volume, inflatable bladders, etc.), may besubstituted in place of a calibrating rod. As another example, while theembodiment of FIG. 3 shows blending a plurality of different fluids inparallel, and the embodiment of FIG. 2 shows the repeated, sequentialdilution of a chemical, those skilled in the art will understand thatvarious combinations of both parallel and sequential mixing schemes arewithin the scope of the present invention. For example, two or moredifferent chemicals can be mixed in parallel, and then the resultantmixture can be mixed with yet other chemicals. These and otherdeviations from the particular embodiments shown will be apparent tothose skilled in the art, particularly in view of the foregoingdisclosure.

We claim:
 1. A fluid delivery system, including at least one measuremodule, said measure module comprising: a fluid inlet port; a vessel forreceiving and retaining a fluid via said fluid inlet port; an aperturepositioned to define a predetermined retention capacity of said vesselby allowing excess fluid to flow out of said vessel; and a fluid outletport for dispensing said retained fluid.
 2. A fluid delivery systemaccording to claim 1, wherein the position of said aperture isadjustable.
 3. A fluid delivery system according to claim 2, whereinsaid aperture is disposed on a vertical drain tube inside said vessel.4. A fluid delivery system according to claim 2, wherein said apertureis disposed in a wall of said vessel.
 5. A fluid delivery systemaccording to claim 1, further comprising a calibrating device foroccupying a portion of said predetermined retention capacity of saidvessel.
 6. A fluid delivery system according to claim 5, wherein saidcalibrating device comprises an adjustable rod.
 7. A fluid deliverysystem according to claim 1, further comprising an overflow reservoir influid communication with said aperture for retaining said excess fluidflowing out of said aperture.
 8. A fluid delivery system according toclaim 7, wherein said overflow reservoir includes an inlet valve tofacilitate selective pressurization.
 9. A fluid delivery systemaccording to claim 8, wherein said overflow reservoir contains at leastone sensor to detect the flow of said excess fluid into said overflowreservoir.
 10. A fluid delivery system according to claim 1, whereinsaid measure module contains at least one sensor for determining whenthe volume of said fluid inside said vessel exceeds said predeterminedretention capacity.
 11. A fluid delivery system according to claim 10,wherein said sensor is adapted to sense said fluid flowing out of saidvessel through said aperture.
 12. A fluid delivery system according toclaim 10, wherein said sensor is adapted to sense when said fluid levelof said vessel has settled at said predetermined retention capacity. 13.A fluid delivery system according to claim 1, further comprising a valvefor selectively coupling said vessel to said fluid inlet port and saidfluid outlet port.
 14. A fluid delivery system according to claim 1,wherein said fluid outlet port contains at least one sensor fordetecting fluid flow out of said vessel.
 15. A fluid delivery systemaccording to claim 1, further comprising a flow controller to controlthe fluid flow rate through said outlet port.
 16. A fluid deliverysystem according to claim 1, further comprising a pressure valve forselectively coupling said vessel with a pressure source.
 17. A fluiddelivery system according to claim 1, further comprising a secondmeasure module, said second measure module comprising: a fluid inletport; a vessel for receiving and retaining a second fluid via said fluidinlet port; an aperture positioned to define a predetermined retentioncapacity of said vessel by allowing excess second fluid to flow out ofsaid vessel; and a fluid outlet port for dispensing said retained secondfluid.
 18. A fluid delivery system according to claim 17, wherein saidoutlet port of said second measure module and said outlet port of saidmeasure module are coupled to a fluid mixing line.
 19. A fluid deliverysystem according to claim 17, further comprising at least one flowcontroller interposed between said fluid mixing line and one of saidoutlet ports of said measure module and said second measure module. 20.A fluid delivery system according to claim 17, further comprising avolume storage module, said volume storage module including: a fluidinlet port for receiving a blended fluid from said fluid mixing line; aholding chamber for storing said blended fluid received from said fluidmixing line; and at least one fluid discharge port for discharging saidstored fluid from said holding chamber.
 21. A fluid delivery systemaccording to claim 20, wherein said volume storage module contains atleast one sensor for generating a fill signal to said measure module andsaid second measure module.
 22. A fluid delivery system according toclaim 20, wherein said volume storage module contains at least onesensor for generating a dispense fluid signal to said measure module andsaid second measure module.
 23. A fluid delivery system according toclaim 20, further comprising a pressure valve to selectively couple saidholding chamber of said volume storage module with a pressure source.24. A fluid delivery system according to claim 20, further comprising anoutlet valve coupled to said fluid discharge port to selectivelyfacilitate fluid flow out of said volume storage module.
 25. A fluiddelivery system according to claim 20, further comprising a secondvolume storage module, including: a fluid inlet port for receiving saidblended fluid from said fluid mixing line; a holding chamber for storingsaid blended fluid received from said fluid mixing line; and at leastone fluid discharge port for discharging said stored fluid from saidholding chamber.
 26. A fluid delivery system according to claim 25,further comprising a first steerage valve for selectively coupling saidfluid mixing line with said fluid inlet port of said volume storagemodule.
 27. A fluid delivery system according to claim 25, furthercomprising a second steerage valve for selectively coupling said fluidmixing line with said fluid inlet port of said second volume storagemodule.
 28. A fluid delivery system according to claim 25, wherein saidfluid delivery system includes a process supply port for providing saidblended fluid to a processing system; and at least one valve forselectively coupling said process supply port with one of said fluiddischarge port of said volume storage module and said fluid dischargeport of said second volume storage module.
 29. A fluid delivery systemaccording to claim 25, wherein said volume storage module receives saidblended fluid from said fluid mixing line while said second volumestorage module dispenses said stored blended fluid via said processsupply port.
 30. A fluid delivery system according to claim 17, furthercomprising a third measure module, said third measure module comprising:a fluid inlet port; a vessel for receiving and retaining a third fluidvia said fluid inlet port; an aperture positioned to define apredetermined retention capacity of said vessel by allowing excess thirdfluid to flow out of said vessel; and a fluid outlet port for dispensingsaid retained third fluid.
 31. A fluid delivery system according toclaim 30, wherein said fluid outlet port of said third measure module iscoupled to said fluid outlet port of said measure module and to saidfluid outlet port of said second measure module via said fluid mixingline.
 32. A fluid delivery system according to claim 30, wherein saidfluid inlet port of said third measure module is coupled to said fluidmixing line to receive said blended fluid.
 33. A fluid delivery systemaccording to claim 32, wherein a volume storage module is interposedbetween said fluid mixing line and said fluid inlet port of said thirdmeasure module.
 34. A fluid delivery system according to claim 30,further comprising a fourth measure module, said fourth measure modulecomprising: a fluid inlet port; a vessel for receiving and retaining afourth fluid via said fluid inlet port; an aperture positioned to definea predetermined retention capacity of said vessel by allowing excessfourth fluid to flow out of said vessel; and a fluid outlet port fordispensing said retained fourth fluid.
 35. A fluid delivery systemaccording to claim 34, wherein said fluid outlet port of said fourthmeasure module and said fluid outlet port of said third measure moduleare coupled to a second fluid mixing line.
 36. A fluid delivery systemaccording to claim 35, wherein said fluid inlet port of said fourthmeasure module is coupled to receive said second fluid.
 37. A fluiddelivery system according to claim 35, wherein said second fluid mixingline is coupled to a process supply port.
 38. A fluid delivery systemaccording to claim 37, wherein a volume storage module is interposedbetween said second fluid mixing line and said process supply port. 39.A method for dispensing a predetermined volume of fluid comprising:filling a vessel with a fluid; draining a portion of said fluid fromsaid vessel via an aperture positioned to define a predeterminedretention capacity of said vessel; and dispensing a remaining portion ofsaid fluid from said vessel.
 40. A method for dispensing a predeterminedvolume of fluid according to claim 39, comprising: filling a secondvessel with a second fluid; draining a portion of said second fluid fromsaid second vessel via an aperture positioned to define a predeterminedretention capacity of said second vessel; and dispensing a remainingportion of said second fluid from said second vessel.
 41. A method fordispensing a predetermined volume of fluid according to claim 40,wherein said step of dispensing said remaining portion of said secondfluid and said step of dispensing said remaining portion of said firstfluid includes blending said first fluid and said second fluid in afluid mixing line.
 42. A method for dispensing a predetermined volume offluid according to claim 40, further comprising: filling a volumestorage module with a blended fluid; storing said blended fluid in achamber of said volume storage module; and dispensing said blended fluidfrom said chamber of said volume storage module.
 43. A method fordispensing a predetermined volume of fluid according to claim 40,further comprising: filling a third vessel with a third fluid; draininga portion of said third fluid from said third vessel via an aperturepositioned to define a predetermined retention capacity of said thirdvessel; and dispensing a remaining portion of said third fluid from saidthird vessel.
 44. A method for dispensing a predetermined volume offluid according to claim 43, wherein said step of dispensing saidremaining portion of said third fluid from said third vessel includesblending said third fluid with said second fluid of said second vesseland said fluid of said vessel in a fluid mixing line.
 45. A method fordispensing a predetermined volume of fluid according to claim 43,wherein said step of filling said third vessel includes filling saidthird vessel with said blended fluid from said fluid mixing line.
 46. Amethod for dispensing a predetermined volume of fluid according to claim44, further comprising: filling a fourth vessel with a fourth fluid;draining a portion of said fourth fluid from said fourth vessel via anaperture positioned to define a predetermined retention capacity of saidfourth vessel; and dispensing a remaining portion of said fourth fluidfrom said fourth vessel.
 47. A method for dispensing a predeterminedvolume of fluid according to claim 46, wherein said steps of dispensingsaid third fluid and dispensing said fourth fluid include blending saidthird fluid and said fourth fluid in a second fluid mixing line.
 48. Afluid delivery system, including at least one measure module, saidmeasure module comprising: a fluid inlet port; a vessel for receiving afluid via said fluid inlet port, and for retaining a predeterminedvolume of said fluid; overflow means for releasing fluid in excess ofsaid predetermined volume from said vessel; and a fluid outlet port fordispensing said retained fluid.
 49. A fluid delivery system according toclaim 48, further comprising a second measure module, said secondmeasure module comprising: a fluid inlet port; a vessel for receiving asecond fluid via said fluid inlet port, and for retaining apredetermined volume of said second fluid; overflow means for releasingfluid in excess of said predetermined volume from said vessel of saidsecond measure module; and a fluid outlet port for dispensing saidretained second fluid.
 50. A fluid delivery system according to claim49, further comprising a means for blending the fluid dispensed by saidmeasure module with said fluid dispensed by said second measure module.51. A fluid delivery system according to claim 49, further comprising athird measure module, said third measure module comprising: a fluidinlet port; a vessel for receiving a third fluid via said fluid inletport, and for retaining a predetermined volume of said third fluid;overflow means for releasing fluid in excess of said predeterminedvolume from said vessel of said third measure module; and a fluid outletport for dispensing said retained second fluid.
 52. A fluid deliverysystem according to claim 51, wherein said fluid inlet port of saidthird measure module is coupled to receive fluid from said outlet portsof said measure module and said second measure module.
 53. A fluiddelivery system according to claim 51, further comprising a means forblending the fluids dispensed by said measure module, said secondmeasure module, and said third measure module.